Overcontrol preventer for miniature captive airplanes



Nov. 12, 1963 M. G. KRETZMER, JR 3,110,126

OVERCONTROL PREVENTER FOR MINIATURE CAPTIVE AIRPLANES Filed Sept. 19.1960 3 Sheets-Sheet l INVENTOR Wfifiebgm/t,

ATTORNEY Nov. 12, 1963 M, G. KRETZMER, JR 3,110,126

OVERCONTROL PREVENTER FOR MINIATURE CAPTIVE AIRPLANES Filed Sept. 19.1960 3 Sheets-Sheet 2 INVENTOR M ATTORNEY OVERCONTROL PREVENTER FORMINIATURE CAPTIVE AIRPLANES Filed Sept. 19. 1960 Nov. 12, 1963 M. G.KRETZMER, JR

3 Sheets-Sheet 3 INVENTOR ATTORNEY United States Patent QVERCSNTR: L F53 IVHMTURE CAPTWE Minor G. Kretzmer, in, Middle liladdam, Conn, as toThe A. (3. Gilbert Company, New Haven, (Iona, a

corporation of Mm'yland Filed Sept. 19, 1969, Ser. No. 57,936 illClaims. (Ql. la- 77) This invention relates to an automatic overcontrolpreenter incorporated in mechanism that transmits to the hand of aground stationed operator the centrifugal pull of an engine propelledtoy or model captive airplane as it circles about the operator.

It is known to mount a transmission mechanism for this purpose on theunder surface of a Wing of the plane to be operated by a pair offlexible control lines reaching inboard of the arc of plane travel tothe operator. Such strands are capable of being seesawed by the hand ofthe operator in a manner to vary the angle oi incline of an aerodynamiccontrol surface in relation to fixed surfaces on the plane while inflight. Such control surface may be that of an elevator swlngable inrelation to a stabilizer to which the elevator is hilged so as to causethe plane to climb or to nose downward at the will of the operator.

it is a general object of these improvements to cause the lirm'ts of therange of movement of an elevator or other plane control surface tobecome varied automatically in accordance with the speed of gyration ofthe plane. Changes in plane speec when launching or landing a toycaptive airplane vary the intensity of centrifugal pull of the plane ina direction outboard of its arc of travel and consequently vary theforce with which the circling plane pulls on the operator held controllines.

A more specific object is so to arrange the speed-deter mined control ofthe limits of elevator movement that for the avoidance of overcontrolsuch range becomes automatically more restricted when the airplane isflying at relatively high speed than when dying at relatively low speed,whereby to compensate for the more sensitive response of the plane tochange of inclination of its elevator or other control surface at thehigher speeds of flight.

Another object is to cause the permissible range of elevator movement tobe thus automatically varied in both directions of elevator swingingmovement.

Anot er object is to provide means whereby there can be variably set andpredetermined the ratio of the range of movement automatically permittedto the elevator to the speed or" the airplane travel.

Another object is to incorporate the improved over-control preventer ina simple unitary mechanism that transmits the pull of the control linesto a direction that accords with the arc of travel of the plane.

Still another object is to construct a unit of transmission mechanism sothat it can readily be attached to or removed from the wing or framework of a toy airplane by simple means such as a couple of small screws.in tms way a given transmission unit is interchangeably applicable todifferent airplanes.

The foregoing and other objects of the invention will be clear ingreater particular from the following description of successfulembodiments of the improvements having reference to the accompanyingdrawings wherein:

FIG. 1 is a perspective view of a self-powered miniature toy or modelcaptive airplane showing the overcontrol preventer of these improvementscarried on the undersurface or" a wing of the plane as when banliing inflight.

PEG. 2 is a bottom plan view or" the overcontrol preventer mounted onthe Wing of tl1 plane with certain parts positioned in accordance withrelatively low speed of plane travel.

FIG. 3 shows certain parts of FIG. 2 shifted automatically in positionto accord with relatively higher speed of plane travel.

FIG. 4 shows certain of the parts or" FIG. 3 rocked to differingpositions by seesawin manipulation of the control lines for causing theplane to climb or to nose downward.

FlG. 5 is a view taken in section on the plane 5-5 in FIG. 2 looking inthe direction of the arrows.

FIG. 6 is a View taken in section on the plane 6--6 in FIG. 2 looking inthe direction of the arrows.

7 is a view similar to FIG. 2 showing a modified cons ruction of theovercontrol preventer likewise embodying the present improvements.

FIG. 8 is a View like FIG. 7 showing certain parts shifted to adifferent relationship automatically caused by increase in speed andcentrifugal pull of the plane.

FIG. 9 shows the parts of FIG. 8 rocked as in PEG. 4 to cause the planeto climb or nose downward at the will oi the operator.

FIG. 10 is a view taken in section on the plane ill-19 in FIG. 7 lookingin the direction of the arrows.

ll is a view taken in section on the plane ill-ll in FIG. 7 looking inthe direction of the arrows.

Flt}. l2 is a view on an enlarged scale taken in section on the plane12-12 in PlG. 7 looking in the direction of the arrows.

Eli i3 is a fragmentary view taken in section on the plane 13-33 in FIG.12 looking in the direction of the arrows.

PEG. 1 shows a miniature toy or model captive airplane having a fuselage'7, a propeller 1% powered by a minature internal combustion engine 9and equipped with landing wheels 8, as it might appear to an operatorstationed on the ground when the plane is banking in flight. Theoperator is assumed to be holding the twin control lin s and 12in amanner to seesaw them or to pull on either line more forcefully than onthe other. A transmission mechanism designated 13 is fastened as a unitto the undersurface of a wing 14 of the airplane and includes a rockerid to which lines ill and 12 are attached on opposits sides of itsfulcrum or pivotal bearing 24. Lines ill and 32 are free to slidethrough guide loops 21 fixed on the win-' surface.

The function of the transmission mechanism '13 is to convert an operatorimposed differential of length between control lines 11 and $12 to anelevator member 15 hinged at the edge or" the fixed stabilizer surface16 by flexible ta es 2 3. The elevator has an aerodynamic controlsurface whose angle of inclination to the stabilizer surface 16 isdetermined by a push-pull connecting rod 17 attached to the same rocker18 as are the control lines 11 and '12.

Connecting rod 17 connects pivotally to the elevator 15 by means of theusual born or coupling bracket 19.

In FIGS. 2 to 5, inclusive, it is shown that the rocker 18 is iulcrumedor pivotally mounted on the aforesaid shiftable bearing 24 which in turnis .carried on a bearing base 23 at slides freely on a guide bracket 25that is fixed to the surface of wing 14 by wood screws 2/ Slide 23contains an elongate slot 22 to accommodate its automatic shiftingmovement relative to guide bracket 25 as hereinafter explained.

The range of swinging movement permitted to rocker is about its bearing24 is limited in each direction of swing by stop devices in partstationed on the guide bracket 25 in the form of stop pin 27 which isencountered by cooperative stop devices in the form of the convexlycurved edge 28 of a stop spur 29 and in the form of conversely curvededge 36 of another stop spur 31. The before mentioned slot 22 in bearingbase 23 straddles stop pin 27 which by encountering opposite ends ofsuch slot can establish positive limits to the extent of sliding thatcan be performed by bearing base 23 relatively to guide bracket '25.Both of the stop spurs 2-9 and 31 are adjustably mounted on rocker 18 bymeans of fastening screws 32 in a considerable choice of positionspermitted by slots 34 and 35 in the respective spurs. Upon beingloosened these screws permit the angular relation of either stop spurand the rocker 18 to be varied to suit the behavior characteristic ofthe toy captive airplane that is to be controlled. it is optional tomake stop pin 27 as a screw stud like stop stud 56 in FIGS. to 13whereby it shall be readily removable to permit unrestricted swinging ofrocker 18 for full control of elevator 15.

As an example or" means to cause the limits of movement of the rocker 18to become automatically varied in accordance with difiering speeds oftravel of a given plane, the bearing base 23 is constantly biased by aspring 33 in a direction toward the fuselage of the plane or in anoutboard directio-n relative to the arc of travel of the plane. Hencethe pull on control lines 11 and 12 is always in opposition to thetension of spring 33 and this pull increases with increase ofcentrifugal force exerted by the plane when flying at relatively. highspeeds of plane travel and becomes less with decreased speed of theplane travel.

In FIGS. 7 to 13, inclusive, a simplified construction is shown whereinthe shiftable bearing base 23 is eliminated and the stop spurs 4t! and41 are formed as an integral part of the modified rocker 42 instead ofbeing adjustable relatively thereto.

The pivotal bearing :for rocker 42 is a simple stud 43 having a thrusthead 44 large enough to overlap the edges of an elongate slot 45 in themodified guide bracket 45. Bracket 46 is fixed securely to the surfaceof the plane wing 14 by the screws 47 in the manner of bracket in FIGS.1 to 6. At an ofiset shoulder portion 48 of bracketv 46 there is fixedlyanchored the free ends 49 of a grasshopper wire spring 59 Whose halfloop in the central portion cradles a grooved wheel 52 on fixed stud 43.Thus a constant bias is exerted on the bearing stud 43 to move towardthe fuselage 7 of the plane relatively to the guide bracket 46 or in anoutward direction in relation to the arc of travel of the plane.

Comparable to the stop pin '27 in FIG. 2, a stop stud 56 is mounted onbracket in the path of swinging movement of the convex edges of the stopspur formationsdl) and 41 on rocker 42. The overall diameter of groovedwheel 52 is sufficiently larger than the width of slot 45 to preventwobbling of stud 43 in such slot and the axial space between the studhead 44 and wheel 52 accommodates free relative sliding movement as wellas free rotary movement between mounting bracket 46 and the rocker 42.

. It will have become apparent from the foregoing description that theamount of play between the convex stop edges of spurs 29 and 31 inrespect to the stop pin 27 as well as the amount of play between thestop edges of spurs 40 and 41 with respect to the stop studs 56automatically becomes less in FIGS. 3 and 8 than it is in FIGS. 2 and 7owing to the fact that the airplane and the guide brackets 25 or 46fixed thereto pull outward away 'from the operator and relatively to thepivotal bearings 24 or 43 which are prevented from correspondinglymoving outward by the hold of the operator on control lines El and 12.Thus in either of FIGS. 2 and 3 or FIGS. 7 and 8 the rocker element 18or 42 is free to be varied in angular disposition by seesawing thecontrol lines 11 and 12 in the usual way to position the elevator 15 atselective angles of inclination for causing the plane to climb or tonose downward.

The abruptness of curvature of the stop edges of the spurs will aifectthe change in limits of rocker movement that will automatically resultfrom given changes in speed of plane travel. If it is desired to removeall restriction of rocker movement, stud will merely be unscrewed frombracket 46 and removed.

Without the automatic variation in the position of the rocker bearing 24or 43 that is provided by these improvements there is a troublesometendency for the operator to swing the rocker such as 13 or 42 a greaterdegree than is needed properly to control the course or" the plane atits differing speeds of travel, as when launching or landing the plane.This diii'iculty becomes automatically eliminated by this inventionbecause the stopsurfaces 28 and 30 or 49 and d1 slant in such directionwith respect to a straight line intersecting the stop abutment 27 or 56and the fulcrum bearing 24 or 43 that when the plane is traveling atrelatively low speed and the pull of centrifugal force exerted by theplane on the control lines 1-1 and -12. consequently is lessened, thedistance between :fulcrum hearing 2 or 43 and the stop abutment 27 or 56becomes shortened by spring 33 or St and a lessened degree of swing ispermitted the rocker element 13 or 42 whereby to prevent overcontrol inthe diflerential manipulation of the control lines by the operator whenthe plane is traveling at relatively low speeds. The novel principlesinvolved in the present improvements as defined the appended claims maybe embodied in various departures from the shapes and arrangements ofparts herein disclosed all of which variations are intended to becovered by the wording of the claims.

What is claimed is:

1. An automatic overcontrol preventer for operating a variablyinclinable aerodynamic control surface in a miniature captive airplane,comprising in combination with framework of the plane and a swingablemember hinged thereon carrying said control surface, a rod connected tosaid member to swing the same, a rocker element operatively linked tosaid rod at a fixed point on said element in a manner to reciprocatesaid member and having attached control lines for manual operationextending away from the airplane in a direction inboard of the arc ofplane travel, a bodily shiftable fulcrum bearing on which said elementis pivoted at a constant distance from said fixed point of rod linkagethereto in a manner to permit rocking of said element about saidbearing, direction determining means on said framework operative toconstrain the bodily shifting of said bearing to directions crosswise ofsaid arc of travel of the captive airplane, resilient means constantlybiasing said bearing relatively to said framework in outboard directionrelative to said arc of plane travel in opposition to the pull of theoperator on said control lines, and stop means in part on said frameworkand in part carried by said rocker element cooperatively disposed tomeet in a manner to limit the extent of rocking "movement of saidelement 2. An automatic overcontrol preventer as defined in claim 1, inwhich the said stop means include a stop.

abutment stationed on the said framework of the airplane, and a stopsurface carried by the said rocker element shaped and disposed to engagewith said stop abutment in a manner to limit the said rocking movementof 7 said element.

3. An automatic overcontrol preventer as defined in claim 2, in whichthe said stop surface is carried on a spur-like plate, together withmeans to fasten said plate in variously adjusted positions on the saidrocker element. 7

4. An automatic overcontrol preventer as defined in claim 2, in whichthe said stop surface is curved conmovement of said element in bothrotary directions thereof. 6. An automatic overcontrol preventer asdefined in claim 5, in which the said stop surfaces are carriedrespectively on separate plates, together with means to fasten saidplates independently of each other in variously adjusted positions onthe said rocker element.

7. An automatic overcontrol preventer as defined in claim 1, in whichthe said resilient means is a cantilever spring engaged with the saidfulcrum bearing in a manner to cause relative movement therebetween whenthe speed of plane travel decreases.

8. An automatic overcontrol preventer as defined in claim 7, in whichthe said cantilever spring comprises a continuous looping of spring Wirehaving a central bowed formation cradling the said fulcrum bearing andfree ends anchored on the said guide bracket.

9. An automatic overcontrol preventer as defined in claim 2, in whichthe said stop surface slants with respect to a straight lineintersecting the said stop abutment and the said fulcrum bearing in suchdirection that automatic shortening of the distance between said bearingand said abutment reduces the degree of rocking movement permitted thesaid rocker element at relatively low speeds or" the plane, whereby toprevent overcontrol of the captive airplane at said low speeds.

10. An automatic overcontrol preventer as defined in claim 5, in whichthe said stop surfaces are located on respectively opposite sides of thesaid abutment and slant with respect to a straight line intersecting thesaid abutment and the said fulcrum bearing in such directions thatautomatic shortening of the distance between said bearing and saidabutment reduces the degree of rocking movement permitted the saidrocker element in respectively opposite rocking directions, whereby toprevent overcontrol of the captive airplane at relatively low speeds ofplane travel.

References Cited in the file of this patent UNITED STATES PATENTS2,490,313 Meister Dec. 6, 1949 2,543,965 Hamilton Mar. 6, 1951 2,570,316Burks Oct. 9, 1951 2,584,588 Hyatt Feb. 5, 1952

1. AN AUTOMATIC OVERCONTROL PREVENTER FOR OPERATING A VARIABLEINCLINABLE AERODYNAMIC CONTROL SURFACE IN A MINIATURE CAPTIVE AIRPLANE,COMPRISING IN COMBINATION WITH FRAMEWORK OF THE PLANE AND A SWINGABLEMEMBER HINGED THEREON CARRYING SAID CONTROL SURFACE, A ROD CONNECTED TOSAID MEMBER TO SWING THE SAME, A ROCKER ELEMENT OPERATIVELY LINKED TOSAID ROD AT A FIXED POINT ON SAID ELEMENT IN A MANNER TO RECIPROCATESAID MEMBER AND HAVING ATTACHED CONTROL LINES FOR MANUAL OPERATIONEXTENDING AWAY FROM THE AIRPLANE IN A DIRECTION INBOARD OF THE ARC OFPLANE TRAVEL, A BODILY SHIFTABLE FULCRUM BEARING ON WHICH SAID ELEMENTIS PIVOTED AT A CONSTANT DISTANCE FROM SAID FIXED POINT OF ROD LINKAGETHERETO IN A MANNER TO PERMIT ROCKING OF SAID ELEMENT ABOUT SAIDBEARING, DIRECTION DETERMINING MEANS ON SAID FRAMEWORK OPERATIVE TOCONSTRAIN THE BODILY SHIFTING OF SAID BEARING TO DIRECTIONS CROSSWISE OFSAID ARC OF TRAVEL OF THE CAPTIVE AIRPLANE, RESILIENT MEANS CONSTANTLYBIASING SAID BEARING RELATIVELY TO SAID FRAMEWORK IN OUTBOARD DIRECTIONRELATIVE TO SAID ARC OF PLANE TRAVEL IN OPPOSITION TO THE PULL OF THEOPERATOR ON SAID CONTROL LINES, AND STOP MEANS IN PART ON SAID FRAMEWORKAND IN PART CARRIED BY SAID ROCKER ELEMENT COOPERATIVELY DISPOSED TOMEET IN A MANNER TO LIMIT THE EXTENT OF ROCKING MOVEMENT OF SAIDELEMENT.